This invention relates to tape reels and, more particularly, to one-piece tape reels for video cassette cartridges.
As described in Assignee's U.S. Pat. No. 4,452,404, and the references cited therein, a tape cassette usually includes a cover, a base and at least one tape reel therebetween. The tape reel usually includes a lower flange, an upper flange, and a hub which is connected centrally between the two flanges. The lower flange can be a separate member connected to the hub, or can be integrally formed with the hub. However, the upper flange is separate and usually connected to the hub by lugs formed on the hub which pass through holes formed in the upper flange. The lugs are then heat deformed, welded or cam locked to hold the upper flange in position relative to the hub. Finally, the hub usually includes centrally of its top surface a pivot button, again either formed separately or integrally therewith. At least the pivot button must be made of a low friction material such as acetal. Thus, with the conventional tape reel, at least two and perhaps four component parts must be produced and assembled.
This type of tape reel is currently widely used because it operates effectively and the manufacturing thereof is not very complicated. However, due to the fact that this conventional tape reel includes several parts that must be separately produced and assembled during manufacture, this tape reel is relatively expensive to manufacture. More particularly, the molding, inventory, assembly and manufacturing yields to make a 2-4 piece tape reel, as well as the difficulty in handling by automation a separate pivot button, lead to relatively expensive production costs.
One piece tape reels have been proposed for minimizing the relatively high manufacturing costs associated with multi-piece tape reels; however, they have not been successful for several reasons. These one-piece tape reels include a hub and upper and lower continuous, planar flanges, all as one piece, requiring a mold which uses side action molding procedures known in the art. Side action causes parting lines to be formed on the tape winding surface of the tape reel, i.e., the hub core outer diameter. Parting lines become an increasing problem as the mold ages. Such parting lines interfere with reliable tape winding and disadvantageously effect tape performance. That is, defects in the surface profile of the core has been known to be related to poor tape performance, dropouts and loss of signal. Further, side action requires large and costly molds which must be run on correspondingly large and costly injection molding machines.
In summary of the prior art, the multi-piece tape reel operates rather efficiently and has been almost unanimously adopted by the industry, but same is relatively expensive to make. On the other hand, one-piece tape reels are aimed at lowering expenses, but interfere with proper tape winding. Therefore, a need exists for an efficiently operating tape reel which is less expensive to make.